使 つかいこなす
tsukaikonasu

Godan Verb (su)

1. to handle (men); to master (a tool); to manage; to acquire a command of (a language)

Transitive
かれ英語 えうごをうまく使 つかいこなす。
karewa ēgō umakutsukaikonasu.
He has a good command of English.
Other forms: